images = [
    "static/image/bg/1.jpg",
    "static/image/bg/2X.jpg",
    "static/image/bg/X3.jpg",
 ]


$(".jumbotron").backstretch(images, {duration: 4000, fade: 800});

setTimeout(function(){
    $("body").data("backstretch").options['fade'] = 2000;
}, 2000);
